3:1 gear

[Jarhead ☠]

So I'm thinking about getting the 3:1 gear for my 1130G, it has the 2:1 now, is it a better ratio for longer bars 36"+?

[lesorubcheek]

I don't have alot of experience with larger trees on an 1130 since most trees around here are smaller, but would think a 3:1 wouldn't really be needed until up in the 40s or even 50+ inch bar. A 1050 can pull a 36" with authority in most cases and it's essentially a 1:1 (no gear reduction) 1130. Of course chain pitch and type, sprocket size and type of wood all have a bearing. Sure a 1/2" pitch chain needs more power than a 404 would too, so a direct comparison between a 1050 and an 1130 isn't really proper unless both using same chain, but I think you get the idea. To really answer this question, run the saw with the bar buried, bearing on it pulling up with the dogs dug in and see if it starts to lug down. If it bogs, consider a 3:1, if it just keeps on piling chips, probably best to leave it alone since the 3:1 is gonna reduce the chain speed.

Dan

[johnly]

I have a 1130G with a 3:1 wearing a 48" .404" bar run by a 8 pin rim drive. The rakers are at .055" right now and I can just get the engine RPMs to drop in 48" of wood with the dawgs set and lifting up on the saw with both hands. If I found a set of 2:1 gears, I would consider myself fortunate.

[sweepleader]

I totally agree with what lesorubcheek said.

Remember that the gear ratio needs to match the power needs of the chain to the power curve of the engine, that is what translates to cutting speed. More aggressive chain (bigger, lower rakers) needs more torque to move wood. Less aggressive chain needs less torque.

But, cutting speed needs to factor in time, torque x speed = horsepower. That is why gear drives are a thing of the past. They waste horsepower in the gears; they take it away from the chain. It is quite a job matching engine power curves to drive ratio to sprocket teeth to chain specs. Modern saws are virtually all direct drive, saving power wasted in the gears for the chain and reducing powerhead weight. They all use smaller chain that can handle the speed of direct drive but would not stand up to a gear drive. Better steels in the cutters stand up better at speed than older alloys.

I think that running the chain as fast as the engine will allow with the engine at the peak of its power curve will move the most wood out of the kerf giving the fastest cutting speed.

The real trick is knowing how much horsepower a chain needs to cut, that is the curve that is unknown but is adjusted for by the sawyer as the chain works its way through the wood.

You guys should swap gears and see what you think, eh?